It had the food tents, the firetrucks parked nearby, the kids running about — I almost rode my bike up to see if I could score some food, but something was off. For starters, it seemed a little closed off, not as spread out and welcoming as your normal picnic.

Also, normal picnics for firefighters don’t have so many people walking around with walkie-talkies.

“It’s a TV show,” one of the walkie-talkie guys told me. “‘Chicago Fire.’”

We chatted a bit. It’s debuting this October. I almost asked which network until I noticed a walkie-talkie woman with a peacock baseball cap. I rode on thinking about the cab company poster on my wall.

The poster is for “The Smartest Choice in Gotham City.” As anyone who has ever taken a taxi in Batman’s fictional home knows, that’s Gotham Cabs. (Boy Wonder Taxis is for suckers.) It’s beautiful, like an art deco woodcut.

I scored it off the “Batman Begins” propmaster. They spent an entire weekend turning a section of lower Michigan into a hobo shanty town, complete with Gotham Cabs ads and fliers for a Thomas and Martha Wayne Foundation gala. To repeat, they made sure their fake Hooverville was made of fake garbage from a fake city and made sure that fake garbage was beautifully designed.

The shanty town was in the background for less than eight seconds. Christian Bale was arguing with Katie Holmes in a car. They didn’t get out of the car.

A year earlier on that same spot, I met Maura Tierney and Goran Višnjić of “ER.” Or more appropriately, yelled “I loved ‘NewsRadio!’” to Tierney as I hauled a leaking garbage bag past the pair.

“ER” was filming a scene on the dock where I worked at the time. It was one of the hottest nights of summer, but the body doubles — and later Tierney and Višnjić, to be fair — were wearing full-length coats. It was going to be a winter scene.

They were right by the bridge where Sean Connery’s beat cop first met Kevin Costner’s Eliot Ness in “The Untouchables.”

Chicago is roughly accustomed to working around filming, but if I’m any example, it’s cute for a while, then you get sick of it.

I liked the conversation I had with a security guard who couldn’t think of the movie star he was guarding (it was Dennis Farina), but I was not amused when Fox’s short-lived “The Chicago Code” kept blocking my street to shoot exterior’s of Jennifer Beals’ character’s house. John Leguizamo’s Christmas comedy kept delaying my bus when I lived in a crappier neighborhood.

But my favorite filming story comes long after the camera stopped. I was looking for parking by some friends’ house in Uptown. I turned on Argyle and freaked the hell out. Essenay Studios. Right there.

Essenay was a silent film studio. And, for a brief year, the Chicago home of Charlie Chaplin.

Lured by big money and lured away by bigger, Chaplin only shot one Essenay film in Chicago — the rest he shot in Essanay’s Niles, Calif., studio. But here was some film history. And not just Chaplin. Ben Turpin. Francis X. Bushman. And a hell of a lot of other stars forgotten to all but nerds like me.

I’m not making a straight line from a studio Charlie Chaplin ended up hating to an NBC fall lineup show about firemen, but Chicago’s got a long past on film. That past filters in when you watch “High Fidelity” or “The Blues Brothers” and realize you’ve been to that L stop, eaten at that restaurant a dozen times.

At that moment, it’s not Cusack, Connery, Bale or Beals up on the screen. As corny as it sounds, it’s you.